I just won a game against a very skilled opponent in which I bought a Transmute but never played it.

Was Fairgrounds or Museum involved?

No - was an IGG/Wall game - I was planning on using it to get rid of Curses and/or pick up a Duchy or 2 but it never connected. In hindsight, it was a bad decision, but my opponent ignored IGG which I think was a worse decision.

Also if you're loading an old game from a replay code, the boons and hexes will always be in the same order as they were in the original game, and the mid-game shuffles will be the same as they were in the original game as well.

I just did the "play treasures, buy Mandarin from Black Market, topdeck treasures, draw treasures, play them again" routine. It's what got me to the $24 I needed to empty the Provinces when I only had $18 in my deck.